Stephen Tvrtko II, also known as Tvrtko Tvrtković, was a member of the House of Kotromanić who reigned as King of Bosnia from 1404 to 1409 and again from 1420 to his death.

The House of Kotromanić was a late medieval Bosnian noble and later royal dynasty. Rising to power in the middle of the 13th century as bans of Bosnia, with control over little more than the valley of the eponymous river, the Kotromanić rulers expanded their realm through a series of conquests to include nearly all of modern-day Bosnia and Herzegovina, large parts of modern-day Croatia and parts of modern-day Serbia and Montenegro, with Tvrtko I eventually establishing the Kingdom of Bosnia in 1377. The Kotromanić intermarried with several southeastern and central European royal houses. The last sovereign, Stephen Tomašević, ruled briefly as Despot of Serbia in 1459 and as King of Bosnia between 1461 and 1463, before losing both countries – and his head – to the Ottoman Turks.